Question

The longitudinal extension of any elastic material is very small. In order to have an appreciable change, the material must be in the form of

• A. thin block of any cross section
• B. thick block of any cross section
• C. long thin wire
• D. short thin wire

Answer 1

Answer: (C)

long thin wire

$\Delta l=\frac{FL}{AY}$
Thus, extension is directly proportional to length and inversely to area. Thus for appreciable extension, length must be long and area less, or long and thin wire